1. Field of the Invention
The present invention relates to an image measuring apparatus and an image measuring method. For example, the invention relates to an image measuring apparatus that performs an operation input for image measurement on an image display and performs measurement through calculation processing on image data. Specifically, the invention relates to an image measuring apparatus and image measuring method that can be appropriately used for a stereo measuring endoscope, for example.
This application claims priority from Japanese Patent Application No. 2006-82393, filed Mar. 24, 2006 and priority from Japanese Patent Application No. 2007-69229, filed Mar. 16, 2007, the contents of which are incorporated herein by reference.
2. Description of the Related Art
An image measuring apparatus is known that performs measurement on an object by imaging the object using, for example, an endoscope and performing image processing for the captured image.
As such a known image measuring apparatus, for example, JP-A-2003-140056 (refer to FIG. 1) discloses an endoscope including a projection unit that projects a pattern image indicating a measurement point on an object, imaging units that are disposed so as to be spaced apart from each other by a predetermined distance in order to perform stereo measurement, and a calculation unit that calculates position coordinates of each measurement point on the basis of a captured image.
Further, JP-A-2005-287900 (refer to FIGS. 1 and 2) discloses a measuring endoscope apparatus that includes an optical adapter for stereo measurement so as to perform stereo measurement. The measuring endoscope apparatus includes a calibration jig for acquiring the mask shape of the optical adapter for stereo measurement.
Furthermore, JP-A-2003-18617 (refer to FIGS. 1 and 5) discloses an imaging apparatus that images parallax images with different amounts of exposure, combines the images by performing gradation conversion so as to be weighted to a main object, acquires an image having a wide dynamic range, and performs stereo measurement using the acquired image.
Since the techniques disclosed in JP-A-2003-140056 and JP-A-2005-287900 are different from each other in that the pattern image at a measurement point is projected in JP-A-2005-287900 and corresponding points of parallax images are detected by matching processing in JP-A-2005-287900, for example, measurement purposes or measurement accuracies thereof are different. However, the techniques disclosed in JP-A-2003-140056 and JP-A-2005-287900 have a three-dimensional coordinate position which is detected on the basis of triangulation using parallax images in common. In these endoscopes, an image of an object is displayed on a monitor or the like and an operator determines a measurement section or a measurement position while observing the image.
In the technique disclosed in JP-A-2003-18617, it may be possible to obtain the same effect as a case of actually widening the dynamic range of an imaging unit.
In addition to the technique disclosed in JP-A-2003-18617, as another example of the so-called wide dynamic range processing, there is a case of increasing the number of gray-scale levels in an arbitrary brightness region in a pseudo manner by image data calculation processing for performing appropriate gradation conversion.